In this paper, we present a new scale detection method for transcription using synchronous addition and subtraction (SAS) processing. And we realized a real-time scale detection system based on this SAS method. A musical instrument sound is sampled synchronously by each scale frequency and their sampled values are accumulated by the SAS method. The accumulated value corresponding to the played scale increases monotonously. From this phenomenon we can detect the scale of a played music sound.
First, we show the principle of the frequency detection using the SAS method, which has two algorithms, a basic algorithm and an improved one. Next, we consider the possibility of scale detection in monophony and polyphony sounds, using the SAS method. And we realize a realtime automatic scale detection system using a PC. Last, we demonstrate the scale detection of piccolo, piano and guitar sounds of an electronic keyboard and clarinet sounds played by an amateur.
